The Obama administration points to checks and balances from Congress as a key rationale for supporting bulk collection of Americans’ telephone communications data, but several lawmakers responsible for overseeing the program in recent years say that they felt limited in their ability to challenge its scope and legality.

The administration argued Friday that lawmakers were fully informed of the surveillance program and voted to keep it in place as recently as 2011. Officials say they have taken unusual steps to make information available to Congress, and committee leaders say they have carefully examined the National Security Agency’s data collection.

Yet some other members of the intelligence and judiciary committees paint a different picture.

They describe regular classified briefings in which intelligence officials would not volunteer details if questions were not asked with absolute precision.